At the moment, if I download a compressed file, it could be any of a .tar.gz archive, a tar.bz2 arhive, a .zip archive or a .gz archive. And each time I do so, I have to remember what the command line options for that program are.

Is there any CLI program where I can just go:

undocompression somefile.??

and let it figure out what format the archive is in? (overly long name used to avoid conflicting with any real program)

It does depend on the version of tar which formats it can autodetect but other than that it works well... IIRC star is actually a more standardized way, where GNU's tar is a non standard extension.
– xenoterracideAug 28 '10 at 17:05

Latest version of GNU tar can uncompress all compressed archives, which are created with any of the compression filter switches (z, j, J, --lzma), it will detect compression automatically.
– polemonNov 29 '10 at 15:58

@xenoterracide: Well, the author of star has criticized GNU tar a lot in his usual style - these writings could be biased (ignoring bad points about star and good points about GNU tar), contain probably some FUD and are probably outdated.
– maxschlepzigNov 29 '10 at 17:29